Dilation catheter with eccentric balloon

ABSTRACT

This invention relates to a balloon dilatation catheter. The balloon dilatation catheter comprises a first, inflation lumen extending therethrough and having distal and proximal ends, the distal end of the first lumen opening into and being in fluid communication with the interior of an inflatable dilatation balloon having distal and proximal ends, and a second lumen extending coextensively with and exterior to the dilatation balloon.

.Iadd.This application is a reissue of Ser. No. 08/111,304, filed Aug.24, 1993, now U.S. Pat. No. 5,413,557, which is a continuation-in-partof Ser. No. 969,946, filed Oct. 30, 1992, now U.S. Pat. No. 5,315,747..Iaddend.

FIELD OF THE INVENTION

This invention is directed to a catheter that utilizes a balloon todilate structures or stenoses within the human body. More particularly,this invention is directed to a dilatation catheter having aneccentrically positioned balloon.

BACKGROUND OF THE INVENTION

The use of balloon catheters to treat strictures, stenoses, ornarrowings within various parts of the human body is well known and isthe subject of many patents. For example, Gruntzig, U.S. Pat. No.4,195,637, Simpson and Robert, U.S. Pat. No. 4,323,071, Bonzel, U.S.Pat. No. 4,762,129, Yock, U.S. Pat. Nos. 5,040,543 and 5,061,273, Samsonet al., U.S. Pat. No. 4,573,470, Chin et al., U.S. Pat. No. 4,493,711,Mueller et al., U.S. Pat. No. 4,790,315, Walinsky et al., U.S. Pat. No.4,641,649Rosen et al., U.S. Pat. No. 4,643,186, and others, teach thatballoon catheters can be used to dilate stenoses in blood vessels. Ineach design, the balloon has a generally cylindrical shape, positionedin a concentric manner in relation to the catheter shaft, and bondeddistally and/or proximally to the shaft. When an operator attempts topass a dilatation balloon pass a dilatation balloon having such a designthrough a very tight opening in a stenosis, the balloon may bunch up,i.e., fold up longitudinally like an accordion, as shown in FIG. 1, andthe catheter will not pass through the stenosis. A balloon catheter inwhich the balloon is bonded to the shaft for its entire length wouldeliminate this problem.

Inflation of a concentrically mounted balloon results in a uniform forcecircumferentially applied to the stenotic lesion. However, the structureor morphology of the lesion is rarely uniform, and harder portions willrequire more force to dilate than will softer areas. This hasnecessitated the practice of inflating the balloon at very highpressures, causing overdistention, dissection, and tearing. In addition,at high pressures, a dilatation balloon may rupture, resulting inserious complications. Thus, there is a need for a balloon catheterwhich can apply a focused, variable force for dilatation, at lowerpressures.

In prior art dilatation balloon catheters, the shaft segment within theballoon may be a solid wire (Frisbee and Samson), or it may be a hollowand open-ended tube which allows the catheter to be moved over aguidewire (Simpson/Robert, Bonzel, Yock). The catheter of Mueller etal., a representative structure of which is shown in FIG. 2, has smallholes in the shaft proximal to the balloon to allow blood to enter, forthe intended purpose of allowing blood to perfuse the vessel while theballoon is inflated. Since the blood impacts the balloon, turns to enterthe small holes in the shaft, and then turns again to exit the catheterin the proximal direction, this design promotes turbulent blood flow ofthe type that often results in hemolysis and thrombosis. The balloon ofWalinsky is porous and is intended to deliver a therapeutic agent to thelesion while the balloon is inflated. Since the inflation pressure ofthe balloon is often high to effect dilatation, the drug may exit thepores in the balloon at a velocity that would injure or even perforatethe vessel.

Thus, there is a need for a balloon dilatation catheter with a lumenpositioned external to the balloon, such that the lumen could be usedfor therapeutic means (e.g., blood perfusion, drug delivery) duringballoon inflation.

OBJECTS OF THE INVENTION

It is an object of the invention to provide a balloon dilatationcatheter that has one or more lumens positioned exterior to the balloon.

It is also an object of the invention to provide a balloon dilatationcatheter in which the balloon is eccentric to the shaft.

It is a further object of the invention to provide a balloon dilatationcatheter in which the balloon is eccentric to a guidewire lumen.

It is yet a further object of the invention to provide a balloondilatation catheter in which the dilating force applied to a strictureis focused and non-uniform around its circumference.

It is furthermore an object of the invention to provide a balloondilatation catheter in which the balloon is attached to the shaft of thecatheter for the entire length of the balloon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional representation of the distal portion of aprior art balloon catheter attempting to cross a tight stenosis;

FIG. 2 is a cross-sectional view of a prior art perfusion catheter;

FIGS. 3 and 3a are each a cross-sectional view of the distal portion ofthe invention illustrating the basic structure of the design.

FIG. 4 is a cross-sectional view of the distal portion of an embodimentof a dilatation balloon catheter according to the invention;

FIG. 5 is a cross-sectional view in the proximal direction of theembodiment shown in FIG. 4;

FIG. 6 is a cross-sectional view through the balloon of the embodimentshown in FIG. 4;

FIGS. 7 and 8 are representations of cross-sections of dilatationballoon catheters according to the prior art and the invention,respectively, within a stricture to be dilated.

FIG. 9 is a cross-sectional view of the distal portion of anotherembodiment of the invention;

FIG. 10 is a cross-sectional view of a further embodiment of theinvention;

FIG. 11 is a cross-sectional view of the line 11--11 of the embodimentshown in FIG. 10; and

FIG. 12 is a cross-sectional view of a yet further embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention herein, the balloon of a balloon dilatationcatheter is mounted eccentric to the catheter shaft, and/or the distalsection of the guidewire lumen. The distal section of the cathetercomprises two or more substantially coextensive lumens wherein thedistal portion of one lumen terminates in a dilatation balloon. Another,second lumen has proximal and distal openings to receive a guidewire ina sliding fit. The second lumen may be of substantially equivalentlength to the first lumen, or, alternatively, be shorter, such that theproximal opening of the second lumen is substantially distal to theproximal opening of the first lumen.

In a preferred embodiment, the catheter comprises two substantiallycoextensive lumens of equal length, wherein the distal portion of onelumen terminates in a dilatation balloon, and the second lumen is openat its distal end and is interrupted near its distal end to provide anopening for a guidewire that extends distally through the open distalend. In this embodiment, the second lumen may have a pushing wire thatextends from the proximal portion of the catheter to a point proximal,adjacent, or distal to the opening. Preferably the second lumen engagesa radiopaque marker that functions to help break plaque as well as toprovide means for locating the position of the catheter balloon withinthe vessel.

The invention can perhaps be better appreciated by making reference tothe drawings. The basic structure of the design is shown in FIGS. 3 and3a. FIGS. 3 and 3a depict the distal portion of a balloon dilatationcatheter 1 having coextensively extending lumens 2 and 3. Lumen 2terminates in a dilatation balloon 4 which is inflated and deflatedthrough lumen 2. Lumen 3 may be bonded to balloon 4 as shown in FIG. 3aor preferably formed from one piece as shown in FIG. 3.

In a preferred embodiment, shown in FIG. 4, lumen 3 contains pushingwire 5, which extends from the proximal end (not shown) of catheter 1 toa position 6 proximal, adjacent to, or within balloon 4. The distalportion of pushing wire 5 is secured by closure, e.g., heat-shrinking,of lumen 3, by insertion of a plug, or by other holding means. Also, thedistal portion 7 of pushing wire 5 is preferably tapered distally toprovide a smooth transition in axial stiffness. The pushing wire 5 willbecome less stiff as the diameter of pushing wire 5 narrows in thedistal direction. The tapering is substantially linear over the distalportion of the pushing wire 5. Optionally, instead of linear tapering,the tapering may be stepped, in discrete reductions, or otherwisenonlinear.

The distal portion 10 of lumen 3 is enlarged, beginning at a locationproximal to the balloon. Opening 9 allows a guidewire 8 to enter andextend distally through the open distal end of lumen 3. Preferably, alubricious lining 14 and a radiopaque marker 15 are included in theenlarged section 10. Lubricious lining 14 may function to hold thedistal portion of pushing wire 5 between the inner surface of lumen 3and the outer surface of lubricious lining 14.

FIG. 5 represents a cross-sectional view showing how lumens 2 and 3relate to one another and how pushing wire 5 is positioned within lumen3. Lumen walls 12 and 13 can each have a thickness of from about 0.3 to20 mil, preferably from about 0.5 to 10 mil.

FIG. 6 represents a cross-sectional view through the center of theballoon of this embodiment. This figure shows how the balloon relates tothe enlarged section 10 of lumen 3, and to guidewire 8. Preferably, aradiopaque marker 15 is sandwiched between the outer surface oflubricious lining 14 and the inner surface of the wall of enlargedsection 10. In an additional embodiment, the catheter may have more thanone external lumen, preferably two.

Although FIGS. 5 and 6 each appear to represent a one-piececonstruction, as shown in FIG. 3a, lumens 2 and 3 may be defined bytubes adhesively or otherwise bonded together.

FIGS. 7 and 8 show dilatation balloon catheters, according to the priorart and the invention, respectively, in the application of dilating astenotic lesion 40 in a blood vessel 41. As the balloon of a dilatationcatheter is inflated, it exerts a force, F, that corresponds to theinflation pressure. The pressure that is exerted against the lesion isproportional to this force, F, divided by the area upon which the forceis acting (the "contact area"). As shown in FIG. 7, for prior artballoon catheters the contact area is equal to the lateral surface areaof the balloon 42. For the catheter of this invention (FIG. 8) thecontact area is not coextensive with the lateral surface area of theballoon 4. At one point the contact area is equal to the lateral surfacearea of balloon 4. However, at another point, the contact area is equalto the lateral surface area of the tube that defines lumen 3. Sincelumen 3 has a much smaller area of contact against the lesion than doesthe balloon 4, the pressure exerted at that point is much greater.Therefore, unnecessarily high balloon inflation pressures can be avoidedsince this design accentuates and focuses the radial force against thelesion adjacent to lumen 3.

The concepts discussed above for FIG. 8 can be representedmathematically by the formulae shown below: ##EQU1## Where P=pressureexerted against a lesion at a given point; F=Force generated byinflating the balloon; and

A=Contact area.

At the location where the balloon 4 makes contact with the lesion 40,the pressure exerted against the lesion is given by ##EQU2## where A_(B)=lateral surface area of the balloon

At the location where the outer wall of lumen 3 makes contact with thelesion 40, the pressure exerted against the lesion is ##EQU3## whereA_(L3) =lateral surface area of the outer wall of lumen 3.

Since the lateral surface area of the balloon is much greater than thatof the outer wall of lumen 3,

    A.sub.B =CA.sub.13                                         (4)

where C=some factor greater than 1.

The ratio of P_(L3) to P_(B) is determined by dividing equation (3) byequation (2) and substituting equation (4) ##EQU4##

Therefore, for a given balloon inflation pressure, the pressure exertedagainst the portion of the lesion adjacent lumen 3 is greater than thatexerted against the portion of the lesion adjacent to the balloon.

Additional embodiments, illustrated in FIGS. 9 to 11, provide foralternate means to achieve the concentration or focusing of the dilatingforce. For both of these embodiments, the section in the eccentric lumen3 that is associated with the dilatation, i.e., adjacent to the balloon,has means that form an even smaller contact area with the lesion. Suchmeans provide somewhat of a sharp edge, similar to a knife edge, to cutthe lesion as the balloon is inflated. In FIG. 9, the metal band 17 thatserves as a radiopaque marker has a triangular shape, and is positionedwithin lumen 3 such that one side of the triangle 17 is located underthe balloon, and the opposite apex of the triangle is against thelesion. In the embodiment of FIGS. 10 and 11, a section of lumen 3 underthe balloon is cut away. A triangularly shaped wire or guidewire, orsome other knife edge or cutting instrument 19, can be safely passedthrough lumen 3 and positioned directly at the lesion through theopening 18. This opening in lumen 3 will also allow drugs to bedelivered directly to the lesion.

The rapid exchange embodiment of the invention, for example, theembodiment shown in FIG. 4, can also function as an improved, moreefficient perfusion catheter. With the guidewire removed from lumen 3,blood will flow through lumen 3 while the balloon is inflated. Since theopenings in lumen 3 are collinear with the artery, i.e., collinear withthe direction of the flow of blood, and are large (compared to theside-hole openings of previously described perfusion catheters), therewill be significantly less turbulence in the blood flow through lumen 3.As a result, there will be significantly greater blood flow, and reducedhemolysis compared to previously described perfusion catheters.Moreover, in an embodiment that employs more than one eccentric lumen,and/or an embodiment like that of FIG. 4 in which pushing wire 5 isreplaced with a sedable guidewire, a guidewire may be left in place(i.e., in a lumen) while blood flows through an open lumen.

According to the invention, the distal section of a balloon dilatationcatheter comprises at least two substantially, longitudinal coextensivelumens wherein one lumen terminates in a dilatation balloon and at leastone other lumen is positioned outside, i.e., eccentric to the balloon.

The lumen walls 12 and 13 are comprised of materials conventional toballoon dilatation catheters. Suitable materials include polyolefinssuch as polyethylene, polyethylene terepthalate, polyurethanes,polyesters, and various copolymers thereof. When used, pushing wire 5can be made from any rigid, medically acceptable material suitable forsuch use, including, but not limited to wires or hypotubes comprised ofstainless steel or other rigid materials.

The construction according to the invention leads to flexibility inproduct design. For example, the choice of pushing wire allows thedesigner to impart various features to the catheter in the form ofvarious flexibility and pushability combinations. Also, a hollow pushingwire, or deletion or removal of the pushing wire, would facilitateinfusion of fluids, drugs, and/or contrast media through the catheterinto the distal vasculature. Similarly, lumen 2, used to inflate theballoon, could have a composite structure, for example, with a distalsegment coextensive with lumen 3 as described above, and a proximalsegment made from a hollow wire, such as a hypotube 50. An example ofsuch an embodiment is shown in FIG. 12. Further, it is within the scopeof the invention that catheter 1 may have at least one additional,coextensive lumen that would similarly facilitate infusion of liquids,drugs and/or contrast media. For example, a catheter 1 with a third,coextensive lumen open at its distal end could have several possibleapplications.

In a preferred embodiment of the invention, as shown in FIG. 4, alubricious coating or a section of thin tubing 14 of lubricious materialis sealed into enlarged section 10. There are several known materialssuitable for this purpose, such as polytetrafluoroethylene (available asTEFLON® from dupont), polyethylenes, polysiloxanes, etc. In thisembodiment the tubing section 14 can hold the distal portion 7 ofpushing wire 5, as well as radiopaque marker 15 or 17, in position.

According to a another embodiment of the invention a slitting means (notshown) is mounted proximally on guidewire 8. Then, as the catheter 1 iswithdrawn, the enlarged section engages the slitting means, the enlargedsection 10 is slit, and catheter 1 is separated from guidewire 8. Thiswould eliminate the requirement for the operator to change hands ascatheter 1 is removed.

The catheter 1 may have visual length markings along its shaft thatwould enable the operator to predict when the catheter 1 would exit theguiding catheter into the vasculature. This would reduce the fluoroscopetime. The preferred design would put the markings directly on thepushing wire 5 (heat shrink tubing rings, inks, paints, etc.). Sincepushing wire 5 is encapsulated within the second lumen 3, the markingswould not be exposed to the patient (i.e., markings would not come off,and materials which could be toxic if exposed may be used).

The preparation of a catheter 1 according to the invention can becarried out by methods and techniques known to or discernible by thoseskilled in the art. Furthermore, preparation of a catheter 1 isdescribed and taught in Applicant's copending, commonly assigned, U.S.patent application Ser. No. 07/969,946, filed Oct. 30, 1992, and U.S.patent application Ser. No. 08/087,428, filed Jul. 2, 1993, both ofwhich are incorporated herein by reference.

Guidewire 8 may be a conventional guidewire, preferably a springguidewire, as is well known. Typical guidewires are shown in U.S. Pat.Nos. 4,757,827, 4,815,478, 4,813,434, 4,619,274, 4,554,929, 4,545,390,4,538,622, 3,906,938, 3,973,556, and 4,719,924, all of which areincorporated herein by reference. In addition, the shaft of guidewire 8could be solid or hollow, such as a hypotube, with an open distal end,to facilitate drug infusion.

Operation and use of the angioplasty apparatus of the invention, anembodiment of which is shown in FIG. 4, may now be briefly described asfollows: A guiding catheter is inserted into the coronary artery in aconventional manner. The guidewire 8 is then introduced into the guidingcatheter and advanced to and across the lesion. Now, the balloondilatation catheter is inserted onto the guidewire and then advancedalong the guidewire 8 to and across the lesion.

After the balloon 4 has crossed the stenosis or lesion, the balloon 4can be inflated in a conventional manner by introducing a radiopaquecontrast liquid through the lumen 2. After the inflation has occurredand the desired operation has been performed by enlarging the opening inthe stenosis, the balloon dilatation catheter 1 can be removed veryrapidly by holding the guidewire 8 stationary and withdrawing theballoon dilation catheter.

If it is ascertained by the operator that additional dilatation of thestenosis is desired and that a larger balloon should be inserted intothe stenosis, this can be accomplished very rapidly by selecting thedesired size of balloon dilation catheter and repeating theaforementioned procedure. The balloon of the new dilatation catheter canbe inflated in the same manner as hereinbefore described. If necessary,even another exchange procedure can be readily accomplished in the samemanner as hereinbefore described utilizing a still larger balloondilatation catheter if that turns out to be necessary.

After the desired amount of dilation of the stenosis or lesion has beenaccomplished, the balloon dilatation catheter can be removed andthereafter the guiding catheter can be removed.

As would be appreciated by those skilled in the art, for embodiments inwhich lumens 2 and 3 are substantially the same lengths, operation anduse of the apparatus would be in the same manner as for a conventionalover-the-wire balloon dilatation catheter.

The preceding specific embodiments are illustrative of the practice ofthe invention. It is to be understood, however, that other expedientsknown to those skilled in the art or disclosed herein, may be employedwithout departing from the spirit of the invention or the scope of theappended claims.

I claim:
 1. A balloon dilatation catheter which comprises:a cathetershaft defining a first, inflation lumen and a second lumen, each of saidfirst and second lumens having proximal and distal ends, and aninflatable dilatation balloon having proximal and distal ends, whereinthe distal end of said first lumen opens into and is in fluidcommunication with the interior of the dilatation balloon and the secondlumen extends longitudinally with the first lumen, the proximal end ofthe second lumen being adjacent to the proximal end of the first lumen,the distal end of the second lumen being open and distal to the distalend of the first lumen, the section of the second lumen distal to theproximal end of the dilatation balloon being exterior to the dilatationballoon, the distal end of the second lumen being open and distal to thedistal end of the dilatation balloon, and the second lumen beingsufficiently linear to allow the catheter to be slidingly advanced overa guidewire.
 2. The catheter of claim 1, wherein the first inflationlumen is a metal hypotube.
 3. The catheter of claim 1, wherein aradiopaque marker is located within the second lumen at a point betweenthe proximal and distal ends of the balloon.
 4. The catheter of claim 3,wherein the radiopaque marker has a triangular shape.
 5. The catheter ofclaim 3, wherein the radiopaque marker has an outwardly extending sharpedge opposite the balloon.
 6. A balloon dilatation catheter system whichcomprises one or more catheters of claim 1 and a guidewire.
 7. Thesystem of claim 6, wherein each catheter has a dilatation balloon ofvarying size.
 8. The catheter of claim 1, wherein a portion of thedistal section of the second lumen has an opening located between theproximal and distal ends of the balloon.
 9. The catheter of claim 8,wherein a cutting instrument may be passed within the second lumen andpositioned at the opening in the second lumen that is located betweenthe proximal and distal ends of the balloon.
 10. The catheter of claim1, comprising one or more additional lumens.
 11. The balloon dilatationcatheter of claim 1, wherein the diameter of the second lumen is smallerthan the diameter of the inflated dilatation balloon.
 12. The balloondilatation catheter of claim 1, wherein the balloon is bonded axiallyalong its entire length to the second lumen.
 13. The balloon dilatationcatheter of claim 1, wherein the balloon and the second lumen are madefrom one piece.
 14. The catheter of claim 1, wherein a radiopaque markeris located within the second lumen at a point between the proximal anddistal ends of the balloon.
 15. The catheter of claim 14, wherein theradiopaque marker has a triangular shape.
 16. The catheter of claim 14,wherein the radiopaque marker has an outwardly extending sharp edgeopposite the balloon.
 17. A balloon dilatation catheter system whichcomprises one or more catheters of claim 1 and a guidewire.
 18. Thesystem of claim 17, wherein each catheter has a dilatation balloon ofvarying size.
 19. A balloon dilatation catheter which comprises:acatheter shaft defining a first, inflation lumen and a second lumen,each of said first and second lumens having proximal and distal ends,and an inflatable dilatation balloon having proximal and distal ends,wherein the distal end of the first lumen opens into and is in fluidcommunication with the interior of the dilatation balloon, the proximalend of the second lumen being open and being located substantiallydistal to the proximal end of the first lumen, the section of the secondlumen distal to the proximal end of the dilatation balloon beingexterior to the dilatation balloon, the distal end of the second lumenbeing open and distal to the distal end of the dilatation balloon, andthe second lumen being sufficiently linear to allow the catheter to beslidingly advanced over a guidewire.
 20. The catheter of claim 19,wherein the diameter of the second lumen is smaller than the diameter ofthe inflated dilatation balloon.
 21. The catheter of claim 19, whereinthe balloon is bonded axially along its entire length to the secondlumen.
 22. The catheter of claim 19, wherein the balloon and the secondlumen are made from one piece.
 23. The catheter of claim 19, wherein thefirst inflation lumen is a metal hypotube.
 24. The catheter of claim 19,wherein a radiopaque marker is located within the second lumen at apoint between the proximal and distal ends of the balloon.
 25. Thecatheter of claim 24, wherein the radiopaque marker has a triangularshape.
 26. The catheter of claim 24, wherein the radiopaque marker hasan outwardly extending sharp edge opposite the balloon.
 27. A balloondilatation catheter system which comprises one or more catheters ofclaim 19 and a guidewire.
 28. The system of claim 27, wherein eachcatheter has a dilatation balloon of varying size.
 29. A balloondilatation catheter which comprisesa first, inflation lumen extendingtherethrough and having distal and proximal ends, the distal end of saidfirst lumen opening into and being in fluid communication with theinterior of an inflatable dilatation balloon having distal and proximalends, and a second lumen extending coextensively with the first lumen,having proximal and distal ends, wherein the proximal end of the secondlumen is adjacent to the proximal end of the first lumen, the distal endof the second lumen is open and distal to the distal end of the balloon,and wherein the distal section of the second lumen is exterior to theballoon and has an opening proximal, adjacent, or distal to the proximalend of the dilatation balloon, and the section of the second lumendistal to the opening is enlarged as compared to the proximal section ofthe second lumen.
 30. The catheter of claim 29, wherein the proximal,unenlarged section of the second lumen contains a pushing wire.
 31. Thecatheter of claim 30, wherein the pushing wire has proximal and distalends and said distal end is positioned at or near the opening of thesecond lumen.
 32. The catheter of claim 29, wherein the enlarged portionof the second lumen comprises lubricious material.
 33. The catheter ofclaim 32, wherein the lubricious material is in the form of tubingwithin the enlarged section.
 34. The catheter of claim 33, wherein thedistal end of the pushing wire is held in position by the lubricioustubing and the second lumen wall.
 35. The catheter of claim 29, whereinthe portion of the second lumen proximal to the opening has been heatshrunk around the pushing wire.
 36. The catheter of claim 29, whichcomprises at least one additional coextensive lumen having open proximaland distal ends.
 37. The catheter of claim 36, wherein there is oneadditional lumen.
 38. The catheter of claim 29, wherein the second lumenis capable of receiving a guidewire in a sliding fit.
 39. The catheterof claim 29, wherein the second lumen comprises lubricious material. 40.The catheter of claim 39, wherein the lubricious material is in the formof tubing within the second lumen.
 41. The catheter of claim 38 whichcomprises at least one additional coextensive lumen having open proximaland distal ends.
 42. The catheter of claim 41, wherein there is oneadditional lumen.
 43. A balloon dilatation catheter system whichcomprises one or more catheters of claim 29 and a guidewire.
 44. Thesystem of claim 43, wherein each catheter has a dilatation balloon ofvarying size.